Benzodiazepine compounds such as diazepam have been used as anti-anxiety drugs for the improvement or treatment of symptoms such as anxiety or tention and the like in neuroses, despression or various diseases. However, these benzodiazepine compounds exhibit unfavarable pharmacological effects such as sedative effect, muscle-relaxant effect, anticonvulsant effect, potentiation of alcoholic effect or potentiation of narcotic effect so that such side effects as drowsiness, dizziness or lowering of attentiveness, concentration or reflex movement-ability have become troublesome problems.
Hence, the developments of more selective anti-anxiety drugs with less or no adverse effects have been desired.
In such investigations of anti-anxiety drugs, non-benzodiazepine compounds having affinity for the benzodiazepine receptor in the brain (e.g., European Patent Application No. 168350 A) are provided. But, the known non-benzodiazepine compounds still have matters to be solved such as insufficient selectivity of anti-anxiety effects or lower safety.
It is known that fuzed pyridazine compounds possess various pharmacological effects. In particular, PCT application under W086/01506 discloses benzo[h]cinnoline compounds such as 9-chloro-2-phenyl-4,4a,5,6-tetrahydrobenzo[h]cinnolin-3(2H)-one which have affinity for the benzodiazepine receptor and exhibit anti-anxiety activity. European Patent Application No. 124314 A and U.S. Pat. No. 4,602,019 specifications indicate, for example, 2,4,4a,5-tetrahydro-7-(1H-imidazol1-yl)-3H-indeno[1,2-a]pyridazin-3-one having cardiotonic and antihypertensive activities. Further, European Patent Application No. 169443 A and U.S. Pat. No. 4,692,447 specifications disclose hypotensive, vasodilating, anti-aggressive, anti-thrombotic and cytoprotective[6,7]-benzocycloheptene-[1,2-c]-pyridazin-3-one compounds represented by, for example, 2-n-butyl-2,4,4a,5,6,7-hexahydro-3H-[6,7]-cyclohepten-[1,2-c]-pyridazin-3- one-8-amino.